This invention relates to a device for dispensing liquid from a liquid container and, more particularly, to a dispense head assembly for dispensing liquid chemical that is designed without O-ring seals to have a reduced number of leak paths, thus minimizing the potential for health risk or environmental hazard from chemical leakage, and minimizing the potential for process fluid contamination.
Dispensing devices are known in the art for dispensing various liquids from containers. In certain applications where the liquid being dispensed is an acid or other such chemical material having known safety and environmental issues, it is desired that the dispensing device be capable of dispensing the liquid without unwanted leakage to the immediate surroundings. For example, certain manufacturing processes require that one or more acid or base material be dispensed into a process fluid handling system. Oftentimes the chemical material is not produced on site and must be provided to the process from a liquid container such as a drum. A dispensing device is attached to the drum to access the chemical material contained therein and to permit the material to be drawn from the container into the process fluid handling system. Once the chemical material in the drum is completely removed, the dispensing device is removed from the spent drum and is attached to a new drum for continued supply of the needed chemical.
A dispensing device designed for use in this manner is known in the art and is disclosed in U.S. Pat. No. 5,878,924. The device disclosed in this patent generally comprises a dispense head assembly that includes a spring-based plunger disposed within a device body, and a lever-lock handle that interacts with the body and that controls the position of the plunger within the body. The body includes an open throat that is in fluid-flow communication with a fluid transfer tube that extends downwardly into a liquid container, i.e., a drum, and a dispense opening perpendicular to the throat. The plunger is disposed within the body and is moved axially upwardly and downwardly therein to respectively close or open the flow of liquid from the throat to the opening. The plunger includes a first circular O-ring seal positioned along a plunger axial end that seats against a horizontal valve seat surface, positioned radially around the throat, to terminate fluid flow. The plunger also includes a second O-ring seal disposed circumferentially around a plunger outside wall surface to form a seal against an opposite body wall surface.
The dispensing device is designed to be attached with a receiver that is mounted to the chemical container and to the fluid transfer tube within the container the device permits fluid flow from the container when the lever-lock handle is locked into a downward position against the body, thereby lifting the plunger within the body so that the first O-ring seal is lifted away from the valve seat surface. The device is designed to terminate fluid flow by lifting and unlocking the lever-lock handle from the body, thereby causing the plunger to be lowered within the body so that the first O-ring seal becomes seated against the valve seat surface. The lever-lock handle allows the dispensing device to be used in a xe2x80x9cfull onxe2x80x9d capacity, when the handle is locked into its downward position, and in an xe2x80x9coffxe2x80x9d position, when the handle is unlocked into its upward position.
The dispensing device so described uses a total of five O-ring seals, two of which are used to provide a seal between the plunger and body, and the other three being used to provide a seal between the body and receiver and fluid transfer tube. A desired feature of dispensing devices used in such application is that it be capable of: (1) providing a high rate of liquid flow therethrough; (2) being operated, i.e., switched from a full onto an off position, easily and reliably; and (3) minimizing the potential of liquid leakage, either resulting in chemical being spilled to the environment or resulting in contaminate material entering the fluid process. For example, when the dispensing device is used to provide high purity chemical material used in a high purity chemical operation, such as in semiconductor manufacturing, it is critical that the process chemical remain contaminate free to ensure the quality of the manufactured product. In practice, it is known that the above-described device includes a large number of potential leak paths, that can cause leakage and/or process contamination resulting from the use of multiple O-ring seals.
It is, therefore, desired that a dispensing device be constructed that is capable of providing a desired high rate of liquid flow therethrough, that can be operated easily and reliably by hand, and that has a minimum number of leak paths to reduce the potential for fluid leakage into the environment, or the potential for the entry of contaminate matter into the fluid handling process.
Dispense head assemblies, constructed according to principles of this invention overcome disadvantages of earlier constructions by both eliminating the need to use O-ring-type seals, and by replacing the conventional plunger with a poppet/rolling diaphragm. Further, dispense head assemblies of this invention comprise a mechanical interlocking system that both prevents the unwanted combination of dispense head assembly members that are used with different process fluids, thereby preventing process fluid contamination, and that prevents the open-flow operation of the assembly until the assembly elements are properly locked into position.
Dispense head assemblies of this invention comprising a housing having a chamber disposed therein that extends from a partially-closed end to an opposite open end. A body is attached to the housing open end and has a fluid passage disposed therein extending between opposite body ends. The fluid passage is in fluid-flow communication with a fluid inlet and a fluid outlet in the body. The fluid passage also includes a circular seal lip located between the fluid inlet and outlet.
A piston is disposed within the body and housing. The piston has a first end that extends through an opening in the partially-closed housing end, and a second end that is attached to a poppet/diaphragm. The poppet/diaphragm extends into the body fluid passage and includes an imperforate head that seats against the seal lip when placed into a closed position, a thin-walled sleeve that extends axially away from the head concentrically along a piston wall surface; and a tongue defining a terminal edge of the sleeve.
A spring is interposed between the piston and the partially-closed housing end to urge the poppet/diaphragm head against the seal lip. A handle is attached at one end to the piston first end to axially move the piston within the assembly between an opened and closed flow position. The poppet/diaphragm sleeve is rolled between opposite piston and assembly wall surfaces when the piston is moved axially within the assembly.
The assembly also includes a dip tube adapter that is attached to the housing and body. The adapter includes a body having a fluid flow passage that extends therethrough from a first end to an opposite second end. The adapter body is designed to form a releasibly locking attachment with an end of the dispense head assembly body. A leak-tight seal is provided between the adapter body and the dispense head assembly body through the use of a tongue and groove sealing arrangement. A dip tube is attached to the second adapter body end to provide fluid pick-up from a fluid container to the dispense head assembly.
A retainer ring is disposed concentrically around the adapter body, and a handle mount is pivotably attached at one handle mount end to the retainer ring. The handle mount is designed to register with the dispense head body when it is attached to the adapter. The handle mount also includes a pivot end that registers with the handle to enable axial piston movement, and related open- and closed-flow assembly operation, when the handle mount is correctly aligned with the dispense head body.